Clay mineral products and their use in rubber compositions

Abstract

Disclosed herein is a rubber composition comprising a rubber and particulate kaolin clay as a filler wherein: the kaolin particles have a particle size distribution such that at least about 95% of the particles, relative to the volume of the particles, have a particle diameter less than 3μm. The particulate kaolin particles may comprise calcined kaolin chosen from at least one of particulate soak calcined kaolin and particulate flash calcined kaolin. The rubber composition can comprise additional particulate fillers including those chosen from silica, carbon black, and other particulate fillers. Also disclosed herein is a process for producing such a composition, and the method of using a cured form of the composition in a rubber composition, such as a vehicle tire composition.

1. A rubber composition comprising rubber and a particulate kaolin clay having a particle size distribution such that at least 95% by volume of the particles have a particle diameter less than 2 μm and greater than 0% and less than 1% by volume of the kaolin particles have a particle diameter between 3 μm and 5 μm, wherein the rubber composition has a first abrasion resistance greater than a second abrasion resistance of the rubber composition being devoid of the particulate kalin clay having said particle size distribution. 
     
     
       2. A rubber composition according to  claim 1 , wherein at least 96% volume of the kaolin particles have a particle diameter less than 2 μm. 
     
     
       3. A rubber composition according to  claim 1 , wherein greater than 0% less than 40% by volume of the kaolin particles have a particle diameter between 1 μm and 5 μm. 
     
     
       4. A rubber composition according to  claim 1 , wherein less than 30% by volume of the kaolin particles have a particle diameter between 1 μm and 5 μm. 
     
     
       5. A rubber composition according to  claim 1 , wherein more than 30% by volume of the kaolin particles have a particle diameter less than 0.5 μm. 
     
     
       6. A rubber composition according to  claim 1 , wherein more than 40% by volume of the kaolin particles have a particle diameter less than 0.5 μm. 
     
     
       7. A rubber composition according to  claim 1 , wherein at least 7% by volume of the kaolin particles have a particle diameter less than 0.2 μm. 
     
     
       8. A rubber composition according to  claim 1 , wherein at least 10% by volume of the kaolin particles have a particle diameter less than 0.2 μm. 
     
     
       9. A rubber composition according to  claim 1 , wherein less than 1% by volume of the kaolin particles have a particle diameter between 3 μm and 5 μm, and less than 40% by volume of the kaolin particles have a particle diameter between 1 μm and 5 μm. 
     
     
       10. A rubber composition according to  claim 1 , wherein the kaolin is a calcined kaolin. 
     
     
       11. A rubber composition according to  claim 10 , wherein the calcined kaolin is a soak calcined kaolin. 
     
     
       12. A rubber composition according to  claim 11 , wherein the calcined kaolin is a flash calcined kaolin. 
     
     
       13. A rubber composition according to  claim 1 , wherein the particulate kaolin clay is present in an amount between 5 phr and 50 phr. 
     
     
       14. A rubber composition according to  claim 1 , further comprising silica. 
     
     
       15. A tire tread formed from a cured rubber composition comprising the rubber composition according to  claim 1 . 
     
     
       16. The tire tread of  claim 15 , wherein the cured rubber composition has a tan δ at 75° C. and 10 Hz less than 0.08 under the test method described herein, together with one or more of: an abrasion resistance under the DIN test method described herein of less than 185 cubic millimeters volume loss; a tensile strength of greater than 25 MPa; a crescent tear strength under the test method described herein of greater than 120 N/mm; and a hardness under the test method described herein of greater than 58 IRHD.